Ester condensation



awns. 1 i 1 K I ,ss'r.-ER 'Co nENsA'1'IoN .7 Virgil HansIey, NiagaraFalls,-N.":.Y.;fassig nor to ES'I. duTontdejNemours;& (Jorru any, Wilf- -.mington, ])e 1 a; cor porationfot'pelaware I QNobrafiinnfhppllcationvMarch 4, .1939;- v I "1 SerialfNo. 259,797 I I I n A. I 2'Claims.- (c1.gso-f-34 5)] I I I I II I This invention relates totnefnrepamnonI r finely diyided state, as the active en'densing" V I condensationproductsof organic compounds and agent. a n -4 l I .7 moreparticularlyto condensations of esters, or of Sodium hydrideof, suitable form,and .-purity l est'ersrvith ketones orarom'atic aldehyd'es. 1 may be conveniently pre pared accordingto the l 5 Thisis a,continuation inrpart.ofymycopending method described in U. S.-Patent 1,958,012.. The 5 applications. N. 87,257, filed June25,'1936,' since hydride obtained by this method is finely divided I iss d a U, s, P t t 2,153,071, I and-hasjapurity of.99-100%. It isbesthandled Condensations of the above type,'general1y re- ,a dt pow er moistened with the'i nert hydrocarq ferred to asfClaisen condensations,Ihavelong ninlwh c it hasbeenp epa Wh n fin ly; I

been known Various condensing age'ntshavediY ded-rsodimn,hydride is coveredwith an inert 10 been used in effecting such. condns'ationsg hydrocarbon such as kerosene, it is practically] Among the mgre common f th r ar tanicj mert tothe atmosphere and may be handled sodium and sodium Jalcoholat'e although sod- 7" w hou d n of p n usly gn gamide; alkali metals other thansodiuni and their" Qd um hydrid p epared by t e, method of a 16 alcoholates'; as well as alkalire'arth metalsand he aboverpatent possesses several adyaritages-li alcoholates of alkali earth, metals likewiselha ve over sodiu -$01 use in the condensation reactb n edin t' gi' ta'h' g tionsunder consideration -vsinc e these conden-,

Condensation reactions ,of the above type in et s=general1y equire temperatures belowthe general have been unimportanteiiceptffrom' a melting-Point Sod m,' he' lattenis generally I no laboratory standpoint since .thewyieldsobtainable subdivide-shy eat nan solvent d are relatively 10w when .condensation's arje caris: s -.@Usua1ly this requires a sol ventldiffer-q 1 ried out by me ns the usual condensingag ents. t o ;.tha i which th rea i is o ta e This is generally due to the" occurrence "of side place. On han so hm-hy ride is o reactions when an alkali metal or alkali earth" fine y d vid d as pr pa ed and an b pr serveda metal is the condensing agent, or to the formadefi te y whsnwet with the inert'organic me-flfi tion of by product alcohol when analcoholate is i m in whi gi is sp -r 1 d p "so-Ia emplcyed; J v I dium hydride possesses to a large measure all Anobject ofthe'present in'vention'is to pin t e co e g rs of-sqdiumfitseh but n improved condensing agent 6 use n retains little or none of the reducing power of a0 condensation reactions involving estersand arosqdiumtowards n l mp u s h a alder'riatic' aldehydes Another object is'to providey -k nes, andesters Thellse of sodiuma condensing agent that doesnot effectreduction hydride t efore elves h e y e d o c d e ofthe reactants or reaction products during such tion P s since yf c e to reduchmderismdfl reactions; Apf rth r objectvis ation of thereactants or reaction products are I niethod for carrying out condensations of esters eliminated; v. Furthermore," condensation reac- 35 and aromatic aldehydes 'whereby good yields 0! films efiected y 'us sodium'hydride pp a condensation products are obtainable. Other obto more direct mth s fl'ec d with sojects will be hereinafter apparent. diurn since during ajcondensation with sodium IIThese object-Snare accomplished in accordance thereaction mixture is deeply colored, whereas I 40 with the present invention'by employing-a metalj When sodium'hydride d ct m x- 40 hydride of an alkali or-alkalineearthmetal as, We remains White or at t y aint wol the active condensing agent. I have found that; Q throughout s rfi y --div ded sodium such hydrides are highly effectiv condensing hydride moistened-'mth'benzene or'kerosen'efis. agents in the- 'abovetype of r'eactions in th'at less hazardous le, l hydmscopicx and condensations may be effected-withhighyieldS more inert Qomtituentsnf the air a 45 of the-v-desired' condensation products} which metaltm-wdumrm the s state i sv d v nyields-are unobtainable, when the previously" --smimm'hydrideisagenqranyivbitterr'iadipted known condensing"agentsfare employed. figgg f g g gfg f gggfiz i sodimln 1 I ,rsessen ayana The alkali meta1= hydndes are especially. l" coholate in its reactions eirc'eptth'at "no, alcohol suited forthe present use, although hydrides or formd a b .l I I I ye roduct fromthe h dride.. es lih g r m tal WlS? m be advan? Since nany a: thesg'reactions are equil i brlum aseo s yem lo ed For reasons which w ll b reaction's'jwith alcohol bein'gja reaction.product,

hereinafter apparent I prefer to practlceiny in-L sodium hydride, is Vparticularlyfus'eful since by vention us ng sodium hydride, preferably in'a its'use a minimum amount of by-product alcohol 55 is formed in the mixture. Another advantage of sodium hydride over sodium alcoholate is that in many cases the reaction mixtures are more fluid when the hydride is used than when an alcoholate is used.

Alkali and alkaline earth metal hydrides and especially sodium hydride may be used to carry out condensations of saturated esters with aromatic aldehydes. condensations may be effected with saturated aliphatic or aromatic esters of low or high molecular weight, provided that one of the ester members has a carbon atom ad-' jacent to the carbonyl radical, which carbon atom is essentially aliphatic in reaction and holds at least one hydrogen atom. Esters which may be used in accordance with the presentinvention" include, among others, the saturated esters of low molecular weight acids, such as acetic, propionic and butyric acids, and the saturated esters of the higher molecular weight acids, such as capric, lauric, myristic, palmitic and stearic acids.

In practicing the present invention to effect condensations between esters and aromatic aldehydes, any aldehyde of aromatic character may be employed, for example, benzaldehyde, naphthaldehyde and furfuraldehyde. Likewise any saturated ester may be used as one of the condensing members provided the ester 'contains'a carbon atom attached to the carbonyl group which is essentially aliphatic in reaction and which has attached thereto at least one hydrogen atom.

In practicing my invention, the amount of alkali or alkaline earth metal hydride employed may vary. When, for example, sodium hydride is employed one mole may be conveniently and effectively used for effecting a condensation'to produce theoretically one mole'oi' reaction product although in some instances it is advantageous to employ twice the above amounts. When the reaction is an equilibrium reaction with a mole of alcohol as a reaction product the use of two moles of metal hydride removescompletely the by-product alcohol and thus effects a more complete reaction in the desired direction. In any case, the amount of hydride employed has but a slight effect on the final cost of the reaction product, especially when sodium hydride is used,

since the molecular weight of the latter is relatively small.

The following examples illustrate a few of the numerous adaptations for which my invention may be used.

Example I Benzaldehyde, 106 grams (1 mole), was added dropwise to a stirred suspension of 30.2 grams (1.26 moles) sodium hydride in 460 cc. (excess) of ethyl acetate cooled to 0 C. The time re quired for the reaction was l.5 hours. The reaction mixture wasthen acidified with acetic acid and worked up in the usual manner. The

yield of distilled ethyl cinnamate was 149v grams or based upon the benzaldehyde used. Example II amount of hydrogen had been evolved the reac-- tion mixture was acidified with acetic acid and methyl cinnamate isolated by distillation. 116 grams of a 72% yield of methyl cinnamate resulted. Along with this 46.5 grams of methyl acetoacetate was obtained (a 30% yield based on the sodium hydride used).

Example III dride suspension. The temperature during this time was maintained at 85-100" C. The reaction mixture then was permitted to cool to 65 C. and was then acidified by adding 0.5 mole of glacial acetic acid and 200 cc. of water. The kerosene solution then was washed with water until free from acid and distilled to recover the product of the condensation reaction, which boiled at 210-220 C. A yield of 67 grams of condensation product was obtained which had a saponification number of 163 and an acid number of 97.2.

Example IV Theprocedure of Example III was followed tocondense furfural with methyl esters of menhaden oil. A mixture of 164 grams of the methyl esters of menhaden oil and 48 grams of furfural was slowly added to a suspension of 15 grams of sodium hydride in 250 cc. oi kerosene. The reactiontemperature was maintained at 75-105 C. Approximately one hour was required for adding the reactants and the reaction mixture then was stirred at about C. for one hour. After acidifying, washing and distilling, as in Example III, a product was obtained boiling at 245-250 C. at a pressure of 15 mm. of mercury. The saponificationj number was 155.5 and the acid number was 4.6.

Example V The method of Example III was used to react fur fural with methyl esters of soya bean oil. A mixture of grams of the ester and 48grams of furfural was added to a kerosene suspension of 15 grams sodium hydride in 250 cc. of kerosene at a temperature of 80-100 C. The product was recovered by acidifying with acetic acid, washed with water and distilled as in Example III. The product had a saponiflcation number of 153 and an acid number of 102.

Example VI Fur-rural was reacted with ethyl propionate in the presence of sodium hydride, utilizing the ethyl propionate as the reaction solvent. The ethyl propionate was cooled to 0 C. and 44.5 grams of sodium hydride was suspended in 400 cc. of the propionate. Furfural was'then slowly added to the suspension while the temperature was maintained at 14-15 C. One hour was required for adding the furfural and the reaction mixture was maintained for about one hour longer at a temperature of 14-15" C. The reaction mixture then was acidified with acetic acid and washed with water. The ester layer was. separated, dried and then distilled in vacuo to remove unreacted ester. A 70% yield of beta-furyl methacrylate was obtained.

Example VII A suspension of sodium hydride was made by adding 30 grams of sodium hydride to 210 grams of ethyl acetate. The suspension was cooled to 10 C. and furfural was slowly added thereto until 96 grams of furfural had been added. The reaction temperature during this time was maintained at 10 to 5 C. The reaction mixture then was acidified with a mixture of HCl gas and anhydrous methanol. The mixture then was filtered and the residue washed with ethyl acetate and the resulting ethyl acetate solution was distilled. A yield of '77 grams (46.4% yield) of ethyl furylacrylate was obtained.

In practicing the present invention, the ester employed as one of the reaction constituents may be conveniently used as the solvent medium for the reaction. However, other solvents which do not react with the reactants or reaction products or with the metal hydride condensing agent may be employed. For example, among other xylene, kerosene, ethers and inert hydrocarbons in general may be advantageously used, especially when the esterv reaction constituent is a solid and when the reaction temperature required is relatively high. When the ester reaction constituent has a high boiling point and is difllcult to distill, the use of an inert solvent in place of an excess of the ester to act as the reaction solvent obviates the necessity of separating the excess ester by distillation from the reaction mixture.

While I have illustrated in the above examples condensations of aromatic aldehydes with esters, effected at temperatures ranging from 10 to over 100 C., it is to be understood that the above temperature ranges are merely illustrative and are not intended to limit the scope of my invention. The reaction temperature to be employed will depend in each case upon the reactants used and the condensation desired. In general, a higher reaction temperature is required as the molecular weight of the ester employed is increased.

I prefer to use sodium hydride as condensing agent in practicing my invention because it is relatively cheap and more conveniently prepared in a suitable state than are other alkali or alkaline earth metal hydrides. Furthermore, I prefer to employ an alkali metal hydride rather than an alkaline earth metal hydride because the alkali metal hydrides may be prepared conveniently at relatively low temperatures in a finely divided state. However, alkaline earth hydrides, such as calcium hydride, may be used effectively as condensing agents in my process.

Many of the compounds which may be prepared in accordance with the present invention have long been important in laboratory syntheses but because of their relatively high cost have found little, if any, use in commercial chemical processes. These compounds may be prepared relatively cheaply and in good yields'by use of the present condensing agents which makes possible an extension of their present uses to commercial fields. For example, the present invention is advantageous for producing alkyl esters of cinnamic acid, as illustrated by Examples I and II. It also provides a new and improved method for producing various condensation products of furfuraldehyde, which have varied uses in the technology of organic chemistry. For example, furfuraldehyde may be reacted with various alkyl esters of the lower fatty acids, for example, the methyl, ethyl and propyl esters of acetic, propionic and butyric acids, to produce various furylacrylates. Thus, with methyl and ethyl acetates, the methyl and ethyl esters, respectively, of furylacrylic acid are obtained; this is illustrated by Example VII. By employing esters of fatty acids having three or more carbon atoms per acid group, alkyl derivatives of the furylacrylates are produced; for example, as shown in Example VI, condensation of furfuraldehyde with an alkyl ester of propionic acid produces the alkyl ester 01 beta-furyl methacrylic acid.

It is understood that the present invention is not limited by the modifications and examples herein disclosed and that any adaptation or modification apparent to a skilled chemist is intended to come within the scope and spirit of the invention.

I claim:

1. A process for preparing ester condensation products comprising reacting a saturated ester with furfuraldehyde in the presence of sodium hydride, said ester having a carbon atom adjacent to the carbonyl group which is essentially aliphatic in reaction and which has attached thereto at least one hydrogen atom.

2. A process for preparing an alkyl furylacrylate which comprises reacting furfuraldehyde with an alkyl acetate in the presence of an alkali 60 metal hydride.

VIRGIL L. HANSIEY. 

